Mu2e: muon-to-electron-conversion experiment

Collaboration

A team of physicists from all over the world, including postdocal
researchers and graduate and undergraduate students, are working together to design, test,
and build the Mu2e experiment. The Mu2e Collaboration is comprised of over two hundred
physicists and continues to grow.

Research goals

Mu2e will have the ability to indirectly probe energy scales well beyond
the terascale being explored at the LHC. At these higher energies the effects of new particles
or new forces may become evident and may provide evidence that the four known forces that govern
particle interations - the gravitational, electromagnetic, weak and strong forces - unify at
some ultra-high energy. (Credit: symmetry magazine/Sandbox Studio)

How it works

The Mu2e detector is a particle physics detector embedded
in a series of superconducting magnets. The magnets are designed to create a low-energy
muon beam that can be stopped in a thin aluminum stopping target and to
provide a constant magnetic field in the detector region that allows the
momentum of the conversion electrons to be accurately determined. (Credit: symmetry magazine)

Research and Development

Physicists verify the expected performance of the Mu2e detector by contructing smaller scale prototype detectors.
They test the performance of the prototypes using Fermilab's testbeam factility or using through-going cosmic rays.

Research and Development

To build the Mu2e experiment will require improving existing technologies and methodologies or inventing new ones.
Measurements are made on a series of thin foils that may be used in an electrostatic septa — a
device that will strip-off a small piece of a circulating proton beam and send it to Mu2e.

In recent years, particle physicists have increasingly turned their attention to finding physics beyond the Standard Model, the current description of the building blocks of matter and how they interact.

Discoveries beyond the Standard Model will help scientists answer some of the most fundamental questions about matter and our universe. Were the forces of nature combined in one unifying force at the time of the Big Bang? How did the universe change from being dominated by energy and radiation remnants from the Big Bang to the one we see today with visible matter, including people and plants?

Addressing these challenging questions will require combining insight and observations from the three discovery frontiers: Cosmic, Energy and Intensity. The linchpin for discovery during the next few decades will be research at the Intensity Frontier on ultra-rare processes, including muon-to-electron conversion. Intensity Frontier searches will provide part of the context to interpret discoveries made on the other frontiers and narrow the number of plausible theories for the origins of physics beyond the Standard Model.

Mu2e will directly probe the Intensity Frontier as well as aid research on the Energy and Cosmic frontiers with precision measurements required to characterize the properties and interactions of new particles discovered at the Intensity Frontier.

Observing muon-to-electron conversion will remove a hurdle to understanding why particles in the same category, or family, decay from heavy to lighter, more stable mass states. Physicists have searched for this since the 1940s. Discovering this is central to understanding what physics lies beyond the Standard Model.

At the most simplistic level, electrons are responsible for the electricity that lights our houses and turns on our computers. Muons are some sort of heavier cousin of the electron, but we're not sure just what the relationship is. This experiment will help us understand that relationship, and so understanding muons is part of understanding the electrons that power our society.

Construction may begin in 2015, commissioning in 2019 and initial preliminary results may be ready about 2020.